Ketopantoate hydroxymethyltransferase (KPHMT) is the first enzyme in the pantothenate biosynthesis pathway. Ketopantoate hydroxymethyltransferase (KPHMT) catalyzes the first committed step in the biosynthesis of pantothenate (vitamin B5), which is a precursor to coenzyme A and is required for penicillin biosynthesis.